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Thread: Brake Proportioning Valve Qusetion

  1. #1

    Question

    I recently installed a big brake upgrade to the Camaro. 4 Piston WilWood Superlites wih 12" x 1.375" rpotors. Everything works fine except that I have thrown the brake balance off. Waaaaayyyy too much front brake now, even with the current proportioning valve cramked all the way to full rears.

    Untill I can aford to update the rear with 4 piston Superlites, ( Currently 1LE setup with PBR calipers and 11.8" rotors ) I was thinking about just switching the Prop valve to the front brakes.

    Don't think it will be a problem, Sprint cars do it all the time, but just wondering about any thoughts on this?

  2. #2

    Post

    Hey Chickenman,

    First thing I would do is sell the camaro and buy a TransAm.

    A prop valve doesnt really alter a the brake balance just the rate in which pressure is applied to the brakes.

    That said I dont know if a prop valve can hide a a really large brake inbalance, particualry for a long brake application (like Knox!).

    Do you think that a 1LE master cylinder would help, you would have to do the numbers as far as the front PBR to your wilwood caliper?

  3. #3

    Post

    Originally posted by Bigger is Better:
    Hey Chickenman,

    First thing I would do is sell the Camaro and buy a TransAm.

    A prop valve doesnt really alter a the brake balance just the rate in which pressure is applied to the brakes.

    That said I dont know if a prop valve can hide a a really large brake inbalance, particualry for a long brake application (like Knox!).

    Do you think that a 1LE master cylinder would help, you would have to do the numbers as far as the front PBR to your wilwood caliper?
    Re: TransAm....why would I want to go slower?

    I probably know the answer to this one myself. Prop valves can handle a fairly large brake imbalance. Most valves can reduce braking pressure to the order of 50%. You're incorrect on your premise that proportioning valves cannot alter the brake balance...that it controls the rate of pressure application only. Aftermarket valves can limit line pressure from 100 PSI to 1,000 PSI. The pressure curve will be linear up to the " Blowoff " pressure, which is usually around 1,000 PSI.

    Master Cylinder is not the problem. GM M\C bores are linear...not stepped. 1LE master cylinder is same as what I run now.

    Swept area is the main problem. Very small pads on the rear. As well the PBR rear calipers have very small cylinders, so clamping forces are reduced.

    The more I read the more I think that this will work. I'm going to test early this year. So if things don't work out I can quickly order some rear Superlite calipers and fix things properly. It's just more money that I didn't want to spend.Still have to buy tires and sort out the suspension and a few other things.

    BTW...have you even installed your WilWood Proportioning valve that was gathering dust for 5 years?

    Ready to get your butt kicked again at Knox?

    [ December 08, 2003, 11:11 AM: Message edited by: Chickenman ]

  4. #4

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Chickenman View Post
    Prop valves can handle a fairly large brake imbalance. Most valves can reduce braking pressure to the order of 50%. You're incorrect on your premise that proportioning valves cannot alter the brake balance...that it controls the rate of pressure application only. Aftermarket valves can limit line pressure from 100 PSI to 1,000 PSI. The pressure curve will be linear up to the " Blowoff " pressure, which is usually around 1,000 PSI.
    Bringing back another old thread to life, so much good info on this forum.

    Currently my civic has a braking problem, I can lockup my tires with only around 20% of pedal travel, making it quite difficult to do precise braking, there is also a bit of rear bias. Based on the post above, am a correct to think that an adjustable brake proportioning valve will allow me to reduce the braking sensitivity as well as to fix the rear bias?
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    2011 Suzuki GSXR600 - Track
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  5. Re: Brake Proportioning Valve Qusetion

    You have two problems and will need to take two steps to adequately fix them.

    Your front to rear brake bias issues can be solved by limiting the maximum brake pressure applied to the rear brakes via a proportioning valve.

    However, it will not have any meaningful effect of increasing the pedal travel to help make modulating easier. For this, you need to reduce the diameter of your master cylinder.

    When we did the 4 wheel brake swap on my Civic, I spent quite a bit of time doing homework to make sure that we ended up with a complete system that worked well - what that took in my car was front and rear DC2 integra calipers, 91 civic EX 4dr 15/16" MC, stock EG booster, and a "4040" proportioning valve which is from a non ABS DC2 Integra (RS model). With this setup, the brakes were AWESOME - modulated nicely, were well balanced front to rear, and had great feel.

    Mark

  6. #6

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by lowside67 View Post
    You have two problems and will need to take two steps to adequately fix them.

    Your front to rear brake bias issues can be solved by limiting the maximum brake pressure applied to the rear brakes via a proportioning valve.

    However, it will not have any meaningful effect of increasing the pedal travel to help make modulating easier. For this, you need to reduce the diameter of your master cylinder.

    Mark
    Thx Mark, when talking to you yesterday, you mentioned that you had the same problem and ended up going with a MC from another civic, which one was that?
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    Carson Au
    2011 Suzuki GSXR600 - Track
    2011 Triumph Speed Triple - Daily
    2001 Toyota Sienna (don't ask...)

  7. Re: Brake Proportioning Valve Qusetion

    Added some more info to my last post.

  8. #8
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    Re: Brake Proportioning Valve Qusetion

    I did the McGyver solution on my Scirocco:

    1. Bought the worst brake shoes I could for the rear
    2. Shaved their edges down for less surface area.

    Carson, it would like you need both a proportioning valve and duller pads on the back.

    And I gotta say, Mark's brakes in the Civic were astonishingly good on the AutoX pad.
    Shift Autosport Inc: 604.568.1848 - 2287 Willingdon Ave, Burnaby

  9. #9

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Sead View Post
    Carson, it would like you need both a proportioning valve and duller pads on the back.
    Good to know, I already have 3rd party "oem" pads, not sure if it could get duller than that, and with HP+ the front they feel pretty balanced. The prob with mixing and matching pads is that when temperature change, the balance changes too.

    I don't know much about adjustable proportioning valves. are they universal? the ones I have seen online don't list application, do I just modify the brake lines to fit it?
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    2011 Suzuki GSXR600 - Track
    2011 Triumph Speed Triple - Daily
    2001 Toyota Sienna (don't ask...)

  10. Re: Brake Proportioning Valve Qusetion

    They are universal, they get spliced into your rear brake hardlines.

  11. #11

    Re: Brake Proportioning Valve Qusetion

    thx mark, thinking of getting something like this:
    http://cgi.ebay.com/ebaymotors/NEW-W...#ht_2185wt_830
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    2011 Suzuki GSXR600 - Track
    2011 Triumph Speed Triple - Daily
    2001 Toyota Sienna (don't ask...)

  12. #12

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Carson View Post
    thx mark, thinking of getting something like this:
    http://cgi.ebay.com/ebaymotors/NEW-W...#ht_2185wt_830
    You don't need one that fancy. That is to replace OEM GM combo valves ( Used on older Vettes I believe ). Would be a hassle to plumb into your Civic.

    Just buy this:

    http://cgi.ebay.com/ebaymotors/NEW-W...item438d4f8d4b

    You might also want to check out the Wilwood lever type valve. Makes in car adjustment a lot easier.

    http://cgi.ebay.com/ebaymotors/NEW-W...item43a2b988de

    BTW. Kratter is an awesome E-bay store for Wilwood Brake Parts. All new products and super prices.

    IMPORTANT!! You have to completely remove the factory combination valve when you install an aftermarket proportioning valve. Failure to do so will result in a horribly long and soft pedal.

    Tee the front brakes together with a brass tee fitting. Run the rear brakes from the proportioning valve to the rear brakes. If you need a hand, I have plenty of experience at this and have the necessary flaring tools and tubing cutters. Give me a call.

    B&J parts in Port Coquitlam also has a great selection of brake adapters. Some odd ball stuff that is hard to find. IE: Pre-made lines with an SAE fitting on one end and Metric on the other. Exactly what you may need for that Wilwood valve. Much better selection than Lordco.

  13. #13

    Re: Brake Proportioning Valve Qusetion

    Carson. You got disc brakes on the rear or drum brakes?

  14. #14

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Chickenman View Post
    IMPORTANT!! You have to completely remove the factory combination valve when you install an aftermarket proportioning valve. Failure to do so will result in a horribly long and soft pedal.

    Tee the front brakes together with a brass tee fitting. Run the rear brakes from the proportioning valve to the rear brakes. If you need a hand, I have plenty of experience at this and have the necessary flaring tools and tubing cutters. Give me a call.
    ^^^ This is very important. If I remember correctly, most FWD cars run a Diagonal-Split brake system (that is, RF and LR run off one cylinder of the master, the LF and RR run off the other - this provides one good front brake in the event of half system failure, as opposed to F/R split, which might leave you with only the "trunk holder upper" brakes should the fronts fail).

    I might be way wrong, however.
    This doesn't put food on your table, it's supposed to be fun. If you're not having fun, you're doing something wrong.
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  15. #15

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Chickenman View Post
    Carson. You got disc brakes on the rear or drum brakes?
    ITR Disc brakes all around.
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    2011 Suzuki GSXR600 - Track
    2011 Triumph Speed Triple - Daily
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  16. #16
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    Re: Brake Proportioning Valve Qusetion

    Btw Canson's Ek civic(NO ABS) is using RSX Type S MC which has ABS. I'm not sure wts the diff for ABS and non ABS MC.

    Yet I'm not sure which proportioning valve he is using.
    2012-13 President, 2011 Rice President, 2010 Director of P????graphy

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  17. #17

    Re: Brake Proportioning Valve Qusetion

    Are you sure you don't have a caliper problem or master cylinder problem in its self?? When did you notice the problem?? How does the peddle feel overall?

    I have seen this kind of thing happen on stock cars where the master cylinder its self is the culprit..

    To run a perportioning valve you will need to redo most of the lines.. As mentioned your system will be a diagonally split system..
    88 multi colourd 323..
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  18. #18

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by SkinnyG View Post
    ^^^ This is very important. If I remember correctly, most FWD cars run a Diagonal-Split brake system (that is, RF and LR run off one cylinder of the master, the LF and RR run off the other - this provides one good front brake in the event of half system failure, as opposed to F/R split, which might leave you with only the "trunk holder upper" brakes should the fronts fail).

    I might be way wrong, however.
    Yes very good point. Lines will have to be changed to F/R split instead of diagonal. Which is another reason why you have to get rid of the factory combo valve. The line rework is not all that hard. You may need two brass tee's instead of one.

    The " safety " aspect of a diagonal split system is a non issue... to me at least. Your opinion may vary. There are no purpose built Race Cars that would ever think of using a diagonal split system. They are all F/R split and for very good reasons.

    1: Next to impossible to design a variable F/R bias system without extremely sophisticated electronics.

    2: Overly complex. More things to go wrong.

    3: Virtually zero safety benefit from a diagonal split system on a race car. Either way, diagonal split or F/R split, if your brakes fail during a Race you are going to be in a world of hurt. Period.

    This is a competition machine and it is expected that the owner would keep his braking system in top order. Also, modern braking systems are pretty darned reliable. They just don't suffer " catastrophic" failures very often.....possible exception being " Vintage " British cars.

  19. #19

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Derek128 View Post
    Btw Canson's Ek civic(NO ABS) is using RSX Type S MC which has ABS. I'm not sure wts the diff for ABS and non ABS MC.

    Yet I'm not sure which proportioning valve he is using.
    Are you saying that the M/C has been changed to something other than what it came equipped with? If so that could be the issue.

    Carson: As others have said, you may want to investigate why the braking is so sensitive. Sounds like the previous owner may have messed things up. You may want to check the M/Cyl part numbers and specs very carefully.

  20. #20

    Re: Brake Proportioning Valve Qusetion

    Quote Originally Posted by Chickenman View Post
    The " safety " aspect of a diagonal split system is a non issue... to me at least.
    On a street-driven vehicle, within our litigious society, it may be an issue. On a trailered race car: give'er.
    This doesn't put food on your table, it's supposed to be fun. If you're not having fun, you're doing something wrong.
    -=- Lethal Locost -=- Lethal Locost 2 -=- V8 Firefly -=- Crusty Chevy -=-

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